The first book I read was the original Dune, and in my opinion that's the best one for a beginner to start, mostly because of the glossary in the back. I haven't read any of the Brian Herbert ones (I haven't even finished the original 6 Frank Herbert books), but in my opinion my favorite is the original.

__________________"Good grief. You guys sure know how to make something out of nothing. And then take sides about whether or not it's nothing, and then change your minds and discuss why you thought it was something." - Kestra